using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.UI;

namespace GameBaseFramework.Extension
{

    /// <summary>
    /// 对 Unity 的扩展方法。
    /// </summary>
    public static class UnityExtension
    {
        private static readonly List<Transform> s_CachedTransforms = new List<Transform>();

        /// <summary>
        /// 获取或增加组件。
        /// </summary>
        /// <typeparam name="T">要获取或增加的组件。</typeparam>
        /// <param name="gameObject">目标对象。</param>
        /// <returns>获取或增加的组件。</returns>
        public static T GetOrAddComponent<T>(this GameObject gameObject) where T : Component
        {
            T component = gameObject.GetComponent<T>();
            if (component == null)
            {
                component = gameObject.AddComponent<T>();
            }

            return component;
        }

        /// <summary>
        /// 获取或增加组件。
        /// </summary>
        /// <param name="gameObject">目标对象。</param>
        /// <param name="type">要获取或增加的组件类型。</param>
        /// <returns>获取或增加的组件。</returns>
        public static Component GetOrAddComponent(this GameObject gameObject, Type type)
        {
            Component component = gameObject.GetComponent(type);
            if (component == null)
            {
                component = gameObject.AddComponent(type);
            }

            return component;
        }

        /// <summary>
        /// 获取 GameObject 是否在场景中。
        /// </summary>
        /// <param name="gameObject">目标对象。</param>
        /// <returns>GameObject 是否在场景中。</returns>
        /// <remarks>若返回 true，表明此 GameObject 是一个场景中的实例对象；若返回 false，表明此 GameObject 是一个 Prefab。</remarks>
        public static bool InScene(this GameObject gameObject)
        {
            return gameObject.scene.name != null;
        }

        /// <summary>
        /// 递归设置游戏对象的层次。
        /// </summary>
        /// <param name="gameObject"><see cref="GameObject" /> 对象。</param>
        /// <param name="layer">目标层次的编号。</param>
        public static void SetLayerRecursively(this GameObject gameObject, int layer)
        {
            gameObject.GetComponentsInChildren(true, s_CachedTransforms);
            for (int i = 0; i < s_CachedTransforms.Count; i++)
            {
                s_CachedTransforms[i].gameObject.layer = layer;
            }

            s_CachedTransforms.Clear();
        }

        /// <summary>
        /// 取 <see cref="Vector3" /> 的 (x, y, z) 转换为 <see cref="Vector2" /> 的 (x, z)。
        /// </summary>
        /// <param name="vector3">要转换的 Vector3。</param>
        /// <returns>转换后的 Vector2。</returns>
        public static Vector2 ToVector2(this Vector3 vector3)
        {
            return new Vector2(vector3.x, vector3.z);
        }

        /// <summary>
        /// 取 <see cref="Vector2" /> 的 (x, y) 转换为 <see cref="Vector3" /> 的 (x, 0, y)。
        /// </summary>
        /// <param name="vector2">要转换的 Vector2。</param>
        /// <returns>转换后的 Vector3。</returns>
        public static Vector3 ToVector3(this Vector2 vector2)
        {
            return new Vector3(vector2.x, 0f, vector2.y);
        }

        /// <summary>
        /// 取 <see cref="Vector2" /> 的 (x, y) 和给定参数 y 转换为 <see cref="Vector3" /> 的 (x, 参数 y, y)。
        /// </summary>
        /// <param name="vector2">要转换的 Vector2。</param>
        /// <param name="y">Vector3 的 y 值。</param>
        /// <returns>转换后的 Vector3。</returns>
        public static Vector3 ToVector3(this Vector2 vector2, float y)
        {
            return new Vector3(vector2.x, y, vector2.y);
        }

        #region Transform

        /// <summary>
        /// 设置绝对位置的 x 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">x 坐标值。</param>
        public static void SetPositionX(this Transform transform, float newValue)
        {
            Vector3 v = transform.position;
            v.x = newValue;
            transform.position = v;
        }

        /// <summary>
        /// 设置绝对位置的 y 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">y 坐标值。</param>
        public static void SetPositionY(this Transform transform, float newValue)
        {
            Vector3 v = transform.position;
            v.y = newValue;
            transform.position = v;
        }

        /// <summary>
        /// 设置绝对位置的 z 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">z 坐标值。</param>
        public static void SetPositionZ(this Transform transform, float newValue)
        {
            Vector3 v = transform.position;
            v.z = newValue;
            transform.position = v;
        }

        /// <summary>
        /// 增加绝对位置的 x 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">x 坐标值增量。</param>
        public static void AddPositionX(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.position;
            v.x += deltaValue;
            transform.position = v;
        }

        /// <summary>
        /// 增加绝对位置的 y 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">y 坐标值增量。</param>
        public static void AddPositionY(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.position;
            v.y += deltaValue;
            transform.position = v;
        }

        /// <summary>
        /// 增加绝对位置的 z 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">z 坐标值增量。</param>
        public static void AddPositionZ(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.position;
            v.z += deltaValue;
            transform.position = v;
        }

        /// <summary>
        /// 设置相对位置的 x 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">x 坐标值。</param>
        public static void SetLocalPositionX(this Transform transform, float newValue)
        {
            Vector3 v = transform.localPosition;
            v.x = newValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 设置相对位置的 y 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">y 坐标值。</param>
        public static void SetLocalPositionY(this Transform transform, float newValue)
        {
            Vector3 v = transform.localPosition;
            v.y = newValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 设置相对位置的 z 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">z 坐标值。</param>
        public static void SetLocalPositionZ(this Transform transform, float newValue)
        {
            Vector3 v = transform.localPosition;
            v.z = newValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 增加相对位置的 x 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">x 坐标值。</param>
        public static void AddLocalPositionX(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localPosition;
            v.x += deltaValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 增加相对位置的 y 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">y 坐标值。</param>
        public static void AddLocalPositionY(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localPosition;
            v.y += deltaValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 增加相对位置的 z 坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">z 坐标值。</param>
        public static void AddLocalPositionZ(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localPosition;
            v.z += deltaValue;
            transform.localPosition = v;
        }

        /// <summary>
        /// 设置相对尺寸的 x 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">x 分量值。</param>
        public static void SetLocalScaleX(this Transform transform, float newValue)
        {
            Vector3 v = transform.localScale;
            v.x = newValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 设置相对尺寸的 y 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">y 分量值。</param>
        public static void SetLocalScaleY(this Transform transform, float newValue)
        {
            Vector3 v = transform.localScale;
            v.y = newValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 设置相对尺寸的 z 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="newValue">z 分量值。</param>
        public static void SetLocalScaleZ(this Transform transform, float newValue)
        {
            Vector3 v = transform.localScale;
            v.z = newValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 增加相对尺寸的 x 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">x 分量增量。</param>
        public static void AddLocalScaleX(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localScale;
            v.x += deltaValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 增加相对尺寸的 y 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">y 分量增量。</param>
        public static void AddLocalScaleY(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localScale;
            v.y += deltaValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 增加相对尺寸的 z 分量。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="deltaValue">z 分量增量。</param>
        public static void AddLocalScaleZ(this Transform transform, float deltaValue)
        {
            Vector3 v = transform.localScale;
            v.z += deltaValue;
            transform.localScale = v;
        }

        /// <summary>
        /// 二维空间下使 <see cref="Transform" /> 指向指向目标点的算法，使用世界坐标。
        /// </summary>
        /// <param name="transform"><see cref="Transform" /> 对象。</param>
        /// <param name="lookAtPoint2D">要朝向的二维坐标点。</param>
        /// <remarks>假定其 forward 向量为 <see cref="Vector3.up" />。</remarks>
        public static void LookAt2D(this Transform transform, Vector2 lookAtPoint2D)
        {
            Vector3 vector = lookAtPoint2D.ToVector3() - transform.position;
            vector.y = 0f;

            if (vector.magnitude > 0f)
            {
                transform.rotation = Quaternion.LookRotation(vector.normalized, Vector3.up);
            }
        }

        /// <summary>
        /// 移除所有子级
        /// </summary>
        /// <param name="transform"></param>
        public static void RemoveAllChilds(this Transform self)
        {
            for (var i = self.childCount - 1; i >= 0; i--)
            {
                GameObject.DestroyImmediate(self.GetChild(i).gameObject);
            }
        }

        #endregion Transform


        #region ContentSizeFitter
        /// <summary>
        /// 立即刷新ContentSizeFitter的尺寸，以
        /// </summary>
        /// <param name="self"></param>
        public static void ForceUpdateSize(this ContentSizeFitter self)
        {
            self.SetLayoutVertical();
            self.SetLayoutHorizontal();
        }
        #endregion


        /// <summary>
        /// 判断是否为空或者数量为0
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        /// <returns></returns>
        public static bool IsNullOrEmpty<T>(this T self) where T : ICollection
        {
            return self == null || self.Count == 0;
        }

        /// <summary>
        /// 判断是否为空或者数量为0
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        /// <returns></returns>
        public static bool IsNullOrEmpty<T>(this ICollection<T> self)
        {
            return self == null || self.Count == 0;
        }

        /// <summary>
        /// 是否为空
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        /// <returns></returns>
        public static bool IsNull<T>(this T self) where T : class
        {
            return self == null;
        }

        /// <summary>
        /// 保持触发事件的唯一
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        public static void AddOnlyListener(this UnityEvent self, UnityAction action)
        {
            self.RemoveAllListeners();
            self.AddListener(action);
        }

        /// <summary>
        /// 保持触发事件的唯一
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        public static void AddOnlyListener<T>(this UnityEvent<T> self, UnityAction<T> action)
        {
            self.RemoveAllListeners();
            self.AddListener(action);
        }

        /// <summary>
        /// 保持触发事件的唯一
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="self"></param>
        public static void AddOnlyListener<T, TR>(this UnityEvent<T, TR> self, UnityAction<T, TR> action)
        {
            self.RemoveAllListeners();
            self.AddListener(action);
        }



    }

}